Content-dependent multipurpose watermarking resistant against generalized copy attack

The paper considers especially attacks that can disclose or counterfeit hidden information. We first explore copy and collage attacks, and find that they can be specified as the generalized copy attack (GCA). Then, we propose to embed a single type of watermark to achieve the multiple purposes of content protection and authentication. Our scheme mainly relies on the deployment of content-dependent watermarks (CDWs), where each is a combination of an informative watermark and a robust hash. Mathematical analyses and experimental results consistently verify the effectiveness of the proposed scheme.